In this Instructable, you will see how to combine the littleBits Synth Kit, littleBits Light Trigger module, some household items, and a Bleep Labs BleepDrum to make light sensitive beat machine. Any drum machine or strobe light can be used to trigger the littleBits synth kit, allowing you to synchronize the tempo between various instruments and the Synth Kit.

Step 1: Gather the Materials

To make a light sensitive beat machine, you will need:
1) littleBits x Korg Synth Kit
2) littleBits Light Trigger module
3) Flashlight with strobe mode (some smart phones may also have a strobe mode or app)
4) Speaker with auxiliary input for other drum machines
5) Drum machine with LED tempo indicator - Bleep Labs BleepDrum used here
6) Plastic tube/cylinder - plastic syringe used here
7) Electrical tape or other opaque tape
8) Utility knife or box cutter

This allows for many possibilities, so look around your house for various light pulsing things!

Step 2: Making a "light Funnel"

In order to make the Light Trigger module sensitive to just a narrow beam of light (like that of an LED), we will make a "light funnel" for the light sensor. Find a plastic tube that is about Sharpie marker sized in diameter. The plastic syringe I found was the perfect size to fit over the light sensor, and the tabs on the end wedged in between the connector ends.

Cut the plastic tube so it is about 2 inches long. Be careful with the utility knife and cut against a solid object (not your leg!).

Wrap electrical tape around the length of the tube. This will block light coming in from the side so that only your desired light source triggers the sequencer. This is similar to the principle of a vactrol, which is often used in modular synthesizers to trigger sounds.

Step 3: Assemble the Synth Kit

In order to trigger the beat with light, the Light Trigger module must be connected to the input of the Sequencer module. The Sequencer module mode should be set to "Step." This means that every time that light changes over the sensor, the sequence will step one beat.

The rest of the Synth Kit can be set up to get the sound you are looking for. Add some filtering, delay, or noise, to taste.

Step 4: Turn Out the Lights, Trigger the Synth, and Dance!

Video 1: Use your flashlight in strobe mode to synchronize your dance party with the music. Make sure your Light Trigger module is set to "Light" mode. Notice in the video that the "light funnel" causes the beat to step only when the strobe light is shined down the tube.

Video 2: Use a drum machine or synthesizer/keyboard that has a tempo light indicator to synchronize the littleBits synth with your drums. The LED on top of the BleepDrum by Bleep Labs fits perfectly in the light funnel. In the video, the BleepDrum is hooked up to the external speaker. The Light Trigger module was set to "Dark" mode, since the LED is just a short pulse, which does not sustain the note on the sequencer.

Play with different light sources. You may need to switch the Light Trigger mode between Light and Dark, as well as adjusting the sensitivity of the sensor.

Have fun making awesome beats!